time machine disk image

[lawrie1947]

Used time machine on mbp for 4 years and just assumed that it backs up files only.
Daft question I guess but does it also back up a disk image by default that I can reboot from if the hard disk fails?

If it does, and I install Yosemite to replace mountain lion, then I will have to create a new backup with Yosemite as the disk image?

My other backup files from previous years will still be available in that case?

Thanks

 

[maflynn]

No, TM does not create a disk image. Carbon Copy Cloner does, so if a bootable image is what you want the CCC is your ticket.

 

[alex0002]

Do you have a Mac that supports Internet Recovery?
Because one of the options available in Internet Recovery, should be to restore from Time Machine backup.

But as maflynn mentions, perhaps the safest method would be to use something like Carbon Copy Cloner before you update to Yosemite.

 

[Weaselboy]

Used time machine on mbp for 4 years and just assumed that it backs up files only.
Daft question I guess but does it also back up a disk image by default that I can reboot from if the hard disk fails?

If it does, and I install Yosemite to replace mountain lion, then I will have to create a new backup with Yosemite as the disk image?

My other backup files from previous years will still be available in that case?

Thanks

A locally attached TM backup disk will do what you want, it just does not work like you think. TM does copy the entire OS etc to the backup disk, but you cannot boot directly to the OS. But what it does do is move a copy of the recovery partition onto the TM backup disk and that can be used to restore a TM backup to a new disk.

So if you put in a new disk you could option key boot to your TM disk and you would see the normal recovery screen. From there you would use disk util to format the new drive then just click restore and it puts the OS and all your apps and data back on the new drive.

If you install Yosemite over top of Mountain Lion, your next backup will be very large to backup the OS changes. After that backup completes you would essentially have a backup of BOTH OS versions on there as long as there is space left on the TM disk.

If you ever went to restore like I mentioned, you would see a screen like this where you could pick a date/OS version to restore from.

The difference between the TM setup I just described and "clone" utilities like Carbon Copy Cloner is you can actually boot directly to the CCC clone and run the computer. Where with TM you would need a new disk and a restore to get back up and running.

If having ability to boot and run from the backup disk it not important to you, TM is all you need.

 

[lawrie1947]

Thanks guys for the input and especially the detailed response here which I do understand.

Cheers

lawrie

A locally attached TM backup disk will do what you want, it just does not work like you think. TM does copy the entire OS etc to the backup disk, but you cannot boot directly to the OS. But what it does do is move a copy of the recovery partition onto the TM backup disk and that can be used to restore a TM backup to a new disk.

So if you put in a new disk you could option key boot to your TM disk and you would see the normal recovery screen. From there you would use disk util to format the new drive then just click restore and it puts the OS and all your apps and data back on the new drive.

If you install Yosemite over top of Mountain Lion, your next backup will be very large to backup the OS changes. After that backup completes you would essentially have a backup of BOTH OS versions on there as long as there is space left on the TM disk.

If you ever went to restore like I mentioned, you would see a screen like this where you could pick a date/OS version to restore from.

Image

The difference between the TM setup I just described and "clone" utilities like Carbon Copy Cloner is you can actually boot directly to the CCC clone and run the computer. Where with TM you would need a new disk and a restore to get back up and running.

If having ability to boot and run from the backup disk it not important to you, TM is all you need.

 

[lawrie1947]

just looked at ccc and may go down that route, just a bit more advice please.

I have a 320 gb hard disk and 500gb ™.

If I delete all but the most recent backups on Time Machine can I partition theTM drive and use CCC on the new partition?

If I do that could I still retrieve old files on the TM partition?

Hope that makes some sense.

 

[Weaselboy]

just looked at ccc and may go down that route, just a bit more advice please.

I have a 320 gb hard disk and 500gb ™.

If I delete all but the most recent backups on Time Machine can I partition theTM drive and use CCC on the new partition?

If I do that could I still retrieve old files on the TM partition?

Hope that makes some sense.

What really matters is how much data is on that 320GB internal?

Normally, you would want the TM partition to be around 1.5X to 2X times the size of the data you ever expect to have on the internal to allow for some storage of versions. So you could have a 320GB internal with 50GB of data and a 100GB or so TM backup disk would be plenty.

With CCC if you just want a straight clone without versions, then the destination would need to be the same size as the data on the internal.

If you can swing it $$, you would be safer using two disks for this so one point of hardware failure does not kill both your backups. That said, it will work fine using two partitions on one disk.

TM is not really designed for you to be able to easily manually shrink the backup set. You would be better off just starting over on the new partition IMO.